Recently, there have been developed various recording mediums in which large-capacity image/sound data and digital data can be recorded. An optical disc such as a DVD (Digital Versatile Disc) can be cited as an example of this kind of recording medium. There has also been developed a large-capacity disc such as a magnetic recording hard disc.
However, in producing a conventional master disc with a visible-range or ultraviolet-range laser beam, recording resolution is restricted by a spot diameter of a recording laser beam. In order to increase the recording density of the above-mentioned disc, it has been studied to perform the production, so-called cutting, of the master disc by a master disc producing apparatus using an electron beam, which has the spot diameter smaller than that of the visible-range or ultraviolet-range laser beam and by which the recording resolution can be improved.
In the production of the master disc, after the electron beam resist is applied onto a substrate, the electron beam is irradiated in a vacuum atmosphere. A latent image of a fine pattern is formed on the electron beam resist by the irradiation of the electron beam (electron beam exposure). A development process, a patterning process, and a resist removing process are performed to the substrate, and a fine convexoconcave pattern is formed on the substrate. Patent Documents 1 and 2 disclose a master disc producing apparatus in which the electron beam is utilized.
In the above-mentioned master disc producing apparatus, the disc substrate onto which the electron beam resist is applied is irradiated with the electron beam while rotated on a rotary stage, so that the fine pattern such as a concentric pattern and a radial pattern is drawn on the disc substrate. Therefore, before the pattern is drawn with the electron beam, it is necessary that objective lens strength and an astigmatism corrector in an electron beam optical system be previously adjusted to narrow the beam diameter. For this reason, it is necessary that a beam adjustment sample be attached in the apparatus or on the substrate. Furthermore, in order to correctly form the concentric or radial fine pattern on the disc substrate, it is necessary that a rotating center of the rotary stage be specified to match a drawing origin of the electron beam with the rotating center of the rotary stage, i.e., with a polar coordinate origin of a rotary linear motion stage system.
Non-Patent Document 1 discloses a beam diameter adjustment technique, wherein the fine-structured adjustment sample attached to a micro-adjustment stage adjacent to the turntable is matched with a substrate height, and the focus adjustment is performed by an electron microscope function possessed by the drawing apparatus of itself such that the resolution of the adjustment sample becomes the best in the electron microscope image.
Non-Patent Document 2 discloses a rotating center adjustment technique, wherein a grating is attached to a center portion of the turntable, and the turntable is rotated to adjust a position of the electron beam.
However, in the beam diameter adjustment technique disclosed in Non-Patent Document 1, because it is necessary that the adjustment sample be moved in an electron beam irradiation range during the adjustment, it is necessary to lengthen a movement distance of a radial-direction moving linear motion stage, which results in a problem that the whole drawing apparatus becomes large. In the case where the drawing apparatus has a function of applying a decelerating voltage for decelerating the electron beam to the substrate as a drawing target, usually the stage on which the adjustment sample is placed is not equipped with a function of applying the decelerating voltage. Therefore, the focal height of the electron beam is different between the substrate surface having a potential of the applied decelerating voltage and the adjustment sample having a ground potential because the decelerating voltage is not applied. Accordingly, in order to correctly perform the beam adjustment in the actual decelerating voltage applied state, decelerating voltage applying means is separately required for the adjustment sample, which results in problems such as complication of an apparatus configuration and cost increase.
On the other hand, in the rotating center adjustment technique disclosed in Non-Patent Document 2, time and effort are required because the grating is attached only in the adjustment while detachment of the grating is required in the actual drawing.
Patent Document 1; Japanese Patent Application Laid-Open No. 2002-367241
Patent Document 2: Japanese Patent Application Laid-Open No. 2003-36572
Non-Patent Document 1. JPN. J. Appl. Phys. Vol. 40, pp 1653-1660, Oct. 30, 2000, “High-Density Recording Using an Electron Beam Recorder”, by Yasumitu Wada, Masahiro Katsumura, Yoshiaki Kojima, Hiroaki Kitahara, and Tetsuya Iida
Non-Patent Document 2: Applied Optics, Vol. 33, No. 10, pp. 2032, April, 1994, “Electron-beam writing system and its application to large and high-density diffractive optic elements”, Shiro Ogata, Masami Tada and Masahiro Yoneda